Heritability of physical activity traits in Brazilian families: the Baependi Heart Study

<p>Abstract</p> <p>Background</p> <p>It is commonly recognized that physical activity has familial aggregation; however, the genetic influences on physical activity phenotypes are not well characterized. This study aimed to (1) estimate the heritability of physical activity traits in Brazilian families; and (2) investigate whether genetic and environmental variance components contribute differently to the expression of these phenotypes in males and females.</p> <p>Methods</p> <p>The sample that constitutes the Baependi Heart Study is comprised of 1,693 individuals in 95 Brazilian families. The phenotypes were self-reported in a questionnaire based on the WHO-MONICA instrument. Variance component approaches, implemented in the SOLAR (Sequential Oligogenic Linkage Analysis Routines) computer package, were applied to estimate the heritability and to evaluate the heterogeneity of variance components by gender on the studied phenotypes.</p> <p>Results</p> <p>The heritability estimates were intermediate (35%) for weekly physical activity among non-sedentary subjects (weekly PA_NS), and low (9-14%) for sedentarism, weekly physical activity (weekly PA), and level of daily physical activity (daily PA). Significant evidence for heterogeneity in variance components by gender was observed for the sedentarism and weekly PA phenotypes. No significant gender differences in genetic or environmental variance components were observed for the weekly PA_NS trait. The daily PA phenotype was predominantly influenced by environmental factors, with larger effects in males than in females.</p> <p>Conclusions</p> <p>Heritability estimates for physical activity phenotypes in this sample of the Brazilian population were significant in both males and females, and varied from low to intermediate magnitude. Significant evidence for heterogeneity in variance components by gender was observed. These data add to the knowledge of the physical activity traits in the Brazilian study population, and are concordant with the notion of significant biological determination in active behavior.</p

Genome-wide linkage scan for exercise participation in Dutch sibling pairs.

This study was aimed at identifying the genomic loci linked to exercise participation in males and females. Cross-sectional exercise data of twins and siblings (18-50 years) were used from the Netherlands Twin Registry. The sample consisted of 1432 genotyped sibling pairs from 622 families (1120 sibling pairs were genotyped on all chromosomes). Exercise participation (no/yes, based on a cutoff criterion of four metabolic equivalents and 60 min weekly) was assessed by survey. Genotyping was based on 361 markers and an average marker density of 10.6 cM. Identical by descent status was estimated for a 1 cM grid. A variance components-based sex-limited linkage scan was carried out for exercise participation. The heritability of exercise participation in males was 68.5% and in females 46.3%. The genetic overlap was estimated at 0.32, indicating that partly different genes affect exercise in the two sexes. Suggestive linkage was found in all subjects on chromosome 19p13.3 (LOD=2.18). Although sex differences in linkage effect were not significant, mainly females contributed to the suggestive linkage. The 19p13.3-13.2 region harbors a number of genes related to muscle performance and muscle blood flow, which might affect exercise behavior through exercise ability. Most likely, a large number of genes with each small effects affect exercise participation in males and females. Large collaborative samples are needed to detect these effects

Anthropometric relationships between parents and children throughout childhood: the Fleurbaix-Laventie Ville Santé Study.

BACKGROUND: The study of parent-child anthropometric relationships and their evolution over time may help to better understand familial risk factors for childhood obesity. METHODS: In a population-based cohort of 124 nuclear families (Fleurbaix-Laventie Ville Sant?tudy (FLVS) I and II), various anthropometric parameters were measured in both parents and their children, first when the children were prepubescent and again at the end of puberty. Troncular adiposity repartition was estimated by calculating troncular to peripheral skinfolds ratio and waist-to-hip circumferences ratio. Birth and infancy heights and weights were also obtained from the children's health booklets. Parent-child correlations were estimated in infancy, before and at the end of the child's puberty. A prospective analysis was performed to predict the changes in the children's measurements over puberty according to their parents' corresponding baseline values. RESULTS: BMI and weight correlations at birth were high (>0.30) with the mother and low (<0.10) with the father, then they converged to an intermediate level at 2 y and remained between 0.2 and 0.3 thereafter. Correlations for waist circumference were already present at the prepubertal period and persisted on the same level at the postpubertal period, whereas correlations for subcutaneous adiposity - measured by four skinfolds - and for adiposity distribution - measured by ratios - were higher at the postpubertal period. Moreover, the prospective approach showed that mother's BMI predicted the evolution of her children's BMI over puberty, whereas this relationship was observed more specifically with the father concerning adiposity distribution parameters. CONCLUSION: Maternal adiposity may act early in life on the adiposity of the child. Maternal and paternal adiposities seem to have quite distinct effects at two key periods of the child's adiposity development such as the prenatal and pubertal periods